Kill, just because you copyright a program doesn't mean that someone else can't make that program. It just means that they can't use code that you wrote without your permission, and they can't modify or steal your program and call it their own. If they just make a program, knowing or not knowing about your own version, it is fine. They cannot get in trouble with it and it is completely legal.

The "no making programs which are the same as programs made by someone else" rule in J2HG has nothing to do with copyright at all. It is just to prevent people from getting mad at each other about stealing ideas, and to prevent competition to make programs better.